Short circuit ratio (SCR) in synchronous dynamoelectric machines is a measure of generator stability or how much the magnetic field in the generator is changed by changes in the load. Higher SCR will improve steady-state stability characteristics of a dynamoelectric machine or a generator. Higher SCR has traditionally been met by the designer either by creating larger machines or by incorporating pole face slots, both of these options have a higher cost associated with them.
Conventional rotors for dynamoelectric machines are generally cylindrically shaped with uniform radial distance between their outer surfaces and the inner surface of their associated stators.